This invention relates in general to welding devices and in particular to a new and useful combination of welding device and undercarriage which permits the welding of foil sheets which are guided in slots on each side of the welding device carried by the undercarriage.
Such a welding machine similar to the invention is known from German Patent No. 27 00 971. In this welding machine, the welding device containing the welding tools and an undercarriage including a frame and two wheels form one solid structural unit. The welding machine is designed so that the wheels run not on the base supporting foil webs to be welded, but on a lower foil web and the lower welding tools grip under the lower foil web in an overlap area, thus forming a bearing surface independent of the base. This makes the welding machine particularly well suited for work on foil webs laid out on an uneven base. But on account of the great weight of the welding machine it can be handled only with great difficulty, when work in a vertical plane or overhead is to be performed, so that it is unsuited for making welding seams on tunnel linings, for example.
The invention provides a welding machine suited for work in both a horizontal and a vertical plane or for overhead work.
Through the measure of detachably connecting the welding device to the undercarriage it can be used selectively with or without an undercarriage. Therefore, if work in a vertical plane or overhead work is to be performed, the weight to be handled can be reduced substantially by removing the undercarriage.
By making the undercarriage height adjustable it is possible to increase the ground clearance of the welding device if the base is especially uneven.
A particularly simple holding means for the welding device comprises a supporting screw connection.
The undercarriage includes a frame with four wheels having the advantage over the known machine, which contains only two wheels, that the machine does not have to be secured against tipping over. One wheel is drivable so that it is possible, in conjunction with a tiltproof design with four wheels that the welding machine can, under certain circumstances, perform the welding operation automatically. The spacing of the wheels is adjustable so that the lateral distance between the wheels and the welding tools can be increased when processing thick or still foil webs, so that the foil web angle between the wheels and the welding tools located higher can be kept flatter. The transversely extending rods are advantageously extensible or retractable for the alteration of the mutual lateral spacing of the wheels.
The undercarriage advantageously includes an obliquely extending roller of the upper foil web so that it is possible to exert such a lateral aligning force upon the upper foil web during the feed motion of the welding device so that the overlap width chosen when laying out the two foil webs to be joined to each other is increased rather than decreased, even under unfavorable circumstances. This assures that the welding seam has a sufficiently great lateral distance from the two web edges everywhere.
By the development according to the invention it is possible, when processing thick or stiff foil strips, to increase the lateral distance betweenthe rollers and the welding tools, whereby the angle of the foil strips between the rollers and the higher lying welding tools can be made flatter. The invention also provides a simple form of realization for varying the mutual lateral distance of the rollers.
The measure according to the invention in which the chassis has an upper foil strip in the form of obliquely set guide rollers it is possible to exert on the foil strip, during the forward movement of the welding apparatus, a lateral straightening (or aligning) force such that the overlap width chosen in laying out the two foil strips to be joined together is rather increased than reduced even under unfavorable circumstances. It is ensured in this way that the weld seam has everywhere a sufficiently great lateral distance from the two strip edges.
By the measure according to which there is a guide edge on the chassis for the foil strips an overlap width of the foil strips uniform over the entire length of the weld seam and hence an always equally wide weld seam can be obtained.
Accordingly it is an object of the invention to provide a welding device for welding machines for operating on foil webs which have edges which are overlapped and wherein the welding device itself is carried on an undercarriage in a manner so that it may be detachably connected to the undercarriage.
A further object of the invention is to provide a welding device which includes an undercarriage made up of a rectangular frame assembly supported on wheels at least one of which has a drive through the welding device for guiding respective edges of foils which are to be overlapped and welded.
A further object of the invention is to provide a welding machine which includes a welding device adjustably carried by an undercarriage which is advantageously height adjustable and in which the device is mounted on supporting screws of the undercarriage which may be adjusted and wherein one of the wheels of the undercarriage is drivable and the spacing between the wheels is adjustable at least laterally by adjusting the transverse members of the frame and wherein the undercarriage includes a front portion having a guide roller for the upper one of the foil webs which are guided through the welding device.
A further object of the invention is to provide a welding machine which is simple in design, rugged in construction and economical to manufacture.